The present invention relates to a control apparatus, an exhaust purifying apparatus for an internal combustion engine, and a control method for an exhaust purifying apparatus.
Nitrogen oxide (NOx) may be included in an exhaust gas exhausted from an internal combustion engine installed in a vehicle or the like. Accordingly, there is a known system that has an injection valve upstream of a selective reduction type NOx catalyst apparatus (SCR) and reduces nitrogen oxide in the exhaust gas by injecting an ammoniacal solution supplied from an ammoniacal solution supply apparatus to an exhaust gas passage through the injection valve.
As for such a system using a reducing agent, JP-A-2008-240546 describes a technique for detecting the concentration of urea water stored in a storage tank using a concentration sensor. In addition, JP-A-2012-2060 describes a technique for determining the quality of the concentration if the detected temperature of urea water is higher than the lower limit of the determinable water temperature set individually in a system that detects the concentration and temperature of urea water in a urea tank.